GASP XXXIX: MeerKAT hunts Jellyfish in A2626

Abstract

We present MeerKAT H i observations of six jellyfish candidate galaxies (JFCGs) in the galaxy cluster, A2626. Two of the six galaxies JW100 and JW103, that were identified as JFCGs from B-band images, are confirmed as jellyfish galaxies (JFGs). Both of the JFGs have low H i content, reside in the cluster core, and move at very high velocities (∼ 3σcl). The other JFCGs, identified as non-jellyfish galaxies, are H i rich, with H i morphologies revealing warps, asymmetries, and possible tidal interactions. Both the A2626 JFGs and three other confirmed JFGs from the GASP sample show that these galaxies are H i stripped but not yet quenched. We detect H i, Hα, and CO(2-1) tails of similar extent (∼ 50 kpc) in JW100. Comparing the multi-phase velocity channels, we do not detect any H i or CO(2-1) emission in the northern section of the tail where Hα emission is present, possibly due to prolonged interaction between the stripped gas and the ICM. We also observe an anti-correlation between H i and CO(2-1), which hints at an efficient conversion of H i to H2 in the southern part of the tail. We find that both RPS and H i-to-H2 conversion are significant depletion channels for atomic gas. H i-to-H2 conversion is more efficient in the disc than in the tail.

3D Modeling of the Molecular Gas Kinematics in Optically Selected Jellyfish Galaxies

“…The best-fit relation obtained by Brown et al (2021) for the VERTICO and HERACLES samples is shown by the dasheddotted line, while its scatter is represented by the shaded area. Deb et al 2020;Ramatsoku et al 2020;Healy et al 2021;Deb et al 2022). Taken together, these results suggest an unusually efficient conversion of H I to H 2 (Moretti et al 2020b).…”

“…This is likely because the stripping is less severe on H 2 than on H I, as the molecular gas is denser and more gravitationally bound to the galaxy than the atomic gas (Lee et al 2017;Boselli et al 2022). The atomic gas disk in our galaxies indeed shows signs of truncation and the ram pressure stripping is much more dramatic than for the molecular gas disk (Ramatsoku et al 2019;Deb et al 2020;Ramatsoku et al 2020;Deb et al 2022).…”

“…Previous works show that, in all the GASP-ALMA galaxies, the stellar kinematics appears to be quite regular, while the ionized gas kinematics is very perturbed, as expected for galaxies undergoing ram pressure stripping (Poggianti et al 2017b;Bellhouse et al 2017;Gullieuszik et al 2017;Jaffé et al 2018;Poggianti et al 2019). Recent works showed that these galaxies host strongly asymmetric H I disks with long tails of atomic gas, and also have significantly reduced H I content with respect to field galaxies (50%; Ramatsoku et al 2019;Deb et al 2020;Ramatsoku et al 2020;Healy et al 2021;Deb et al 2022). This H I deficiency is, however, not coupled with a deficiency in the molecular gas reservoir, as these galaxies have H 2 masses that are 4-5 times higher than expected for galaxies with similar stellar mass (Moretti et al 2020a(Moretti et al , 2020b.…”

“…Indeed, cluster galaxies often contain less atomic gas than expected from their optical size or stellar mass and have truncated and/or asymmetric H I disks (Chamaraux et al 1980;Haynes et al 1984;Giovanelli & Haynes 1985;Cayatte et al 1990;Schröder et al 2001;Solanes et al 2001;Waugh et al 2002;Chung et al 2009;Loni et al 2021;Zabel et al 2022). Morever, long tails of atomic gas are commonly observed in cluster galaxies (Bravo-Alfaro et al 2000;Kenney et al 2004;Chung et al 2007;Scott et al 2010;Sorgho et al 2017;Ramatsoku et al 2019;Deb et al 2020;Ramatsoku et al 2020;Healy et al 2021;Deb et al 2022;Hess et al 2022).…”

“…The GASP survey aims at understanding the impact of environment on the evolution of galaxies by studying their stellar and ionized gas emission. Recently, follow-up programs have provided multiwavelength observations for a few galaxies in the GASP sample, allowing one to study other ISM components, such as atomic gas (Ramatsoku et al 2019;Deb et al 2020;Ramatsoku et al 2020;Healy et al 2021;Deb et al 2022;Luber et al 2022), molecular gas (Moretti et al 2018(Moretti et al , 2020a(Moretti et al , 2020b, magnetic fields (Müller et al 2021), and also young stellar populations (George et al 2018). An unexpected result of the GASP project was the high fraction of active galactic nuclei (AGNs) among ram-pressure-stripped galaxies (Poggianti et al 2017a;Peluso et al 2022;Poggianti & the GASP team 2022).…”